The statements in this section merely provide background information related to the present disclosure and are not admitted as prior art.
With propagation of smartphones with improved performance and abrupt increase in the number of content providers on the basis of the propagation of smartphones, traffic of mobile communication networks increases, resulting in service quality deterioration due to a decrease in download speed and a transmission rate of content such as video, audio, images, applications, etc.
With the development of content transmission technologies, large-capacity file transmission can be achieved when online video services such as VOD (Video On Demand), live streaming, etc. are provided or music streaming, file upload and download, etc. are performed, and thus various services for delivering large-capacity content are provided.
However, these content providing services deliver redundant content to users in the same domain or the same radio coverage in general although the frequency of delivery of content depends on the popularity of the content, and transmitted content is beginning to represent an increasing share of network traffic as the content providing services are increasingly used.
In a situation that traffic of a communication network abruptly increases due to transmission of large-capacity content, the inventor(s) has experienced that transmission of redundant content further increases a traffic load of the communication network.
In view of this, a CDN (Content Delivery Network) service stably delivers various types of content including moving images such as movies, music video, etc. to users. The CDN service is implemented in such a manner that content is stored in a plurality of local caching devices distributed in a network, a most suitable cache server is selected from a plurality of cache servers through a load balancer such as a GLB (Global Load Balance) server and requested content is delivered to a user equipment through the selected cache server.
The CDN was implemented on the basis of the Internet in order to solve problems including data loss, bottlenecks, transmission rate decrease, instability such as discontinuous data transmission, etc.
Content caching is a technology of selectively caching content in a plurality of local caching devices distributed in a network in the CDN service. Content caching is performed in consideration of the size of a storage space of a local caching device. Furthermore, the inventor(s) has noted that it is necessary to consider a time required to determine whether cached content includes content corresponding to content requested by a user and a cache hit rate corresponding to the rate at which content requested by a user corresponds to cached content.